(1) Field of the Invention
The present invention relates to outdoor advertising signs, and in particular to signs including means for permitting rotation of the sign advertising display about a vertical axis when the wind force exceeds a predetermined value.
(2) Description of the Prior Art
Large outdoor advertising signs, also known as billboards, are comprised of an upper rectangular advertising display assembly, or simply display, supported on and elevated for viewing on a support pole or column. The advertising display may be constructed in different ways, but generally includes a frame having parallel upper and lower edges, and parallel side edges. The frame surrounds a rectangular panel for placement of advertisements. In most signs, the frame will surround two spaced panels with one or both panels carrying advertising messages, such as the name of a business. The panels are normally parallel translucent panels that are spaced from each other, with an illumination source, such as a lighting fixture being positioned between the panels to back light the panels. The illumination source is connected via wiring to an external source of electricity.
The support column is comprised of a generally cylindrical vertical column having an upper end upon which the advertising display is mounted. Sign columns are now often constructed of steel, permitting the support of larger advertising displays at greater heights above the ground.
Signs are subject to wind damage, particularly in hurricane prone areas, due to the large surface area presented by the advertising display when the display is transverse to the wind direction, either at the front or back of the display. High winds can cause severe damage to advertising displays, and even to the support structures, as well as to persons or property in the vicinity of the sign if a part of the sign is separated from the structure. Such damage requires costly replacement and repair. Construction of signs to withstand greater wind forces also results in additional cost.
Various attempts have been made in the prior art to avoid damage to signs by constructing the signs with pivotal advertising displays that rotate to present a reduced surface to the wind direction when a wind force exceeding a predetermined value, e.g., 60 mph, is experienced. Generally, these prior art signs include a pivotal support for the advertising display and a pin that holds the display in place until the wind force exceeded the predetermined value. When there is excess wind force against the display, the pin is designed to shear off or displace from a detent, allowing the display to rotate about a pivot point so that the display face is parallel to the wind direction, i.e., so that an edge of the display is toward the wind direction, thereby presenting a smaller surface to wind impact and reducing the likelihood of damage.
While sign constructions described in the prior art may have been of some value in diminishing damage to signs as historically constructed, they are of little value in preventing damage to modern signs. Therefore, there is a continuing need for a sign, particularly an electrically illuminated sign, meeting the demands of modern sign construction that will withstand damage from high winds, e.g., winds exceeding 60 mph.